The invention is concerned with electromagnetically controllable couplings connecting the drive shaft of a textile machine with a cam means operating to control the displacement of the guide bars. These couplings are electromagnetically controlled by the interaction of an electromagnet and an anchor means attached to the coupling means.
In a coupling means of the art (German patent DE-PS No. 27 41200 FIG. 4) the anchor provided to each electromagnet stops the movement of an intermediate lever in the inactive position, said intermediate lever controlling a latch which interacts between the coupling means and the drive shaft itself. When the programming arrangements provides activation current to the electromagnet and the anchor is attracted, the intermediate lever is freed and the rocker arm biased by a spring attached thereto, moves into a second position in which it no longer acts upon the latch. This mode of construction requires a plurality of interacting parts, this in turn limits the working speed of the device. The stopping of the intermediate lever is effected by an edge which, in time, will become abraded. The safety factor thus will eventually be reduced. In order to insure that the anchor is certain to be attracted, it is necessary to utilize a relatively large activation current. This, of course, requires the use of a relatively more substantial activation winding.
When the coupling is utilized to obtain a particular, patterning for example, by combination with similar couplings to influence the displacement movement of a guide bar of a warp knitting machine (for example, Germany published application DE AS No. 2610888) a further disadvantage occurs in that in the event of subsequent power failure or other emergency switch off of the machine, the orientation of the rocker arm can no longer be controlled. The appropriate cam elements therefore are in an uncertain position and thus on reactivation of the machine pattern confusion will result.
The problem to be solved therefore, is to provide a coupling of, a type heretofore described which is simpler in construction, avoids the problem of current failure and is operable with a lower activation current.